Nutritional ecology of the formosan subterranean termite (Isoptera: Rhinotermitidae): feeding response to commercial wood species

The feeding preferences of the Formosan subterranean termite, Coptotermes formosanus Shiraki, were tested in three separate experiments on 28 different wood species. Experiment 1 was a multiple-choice test designed to test relative preferences among 24 wood species commercially available in New Orleans, LA. Experiment 2 was a similar study designed to test relative preferences among 21 wood species shown or reported to be unpalatable to the Formosan subterranean termite. Experiment 3 was a no-choice test to examine the feeding deterrence of the 10 least preferred wood species. Preference was determined by consumption rates. Birch (Betula alleghaniensis Britton), red gum (Liquidambar styraciflua L.), Parana pine [Araucaria angustifolia (Bert.) 1, sugar maple (Acer saccharum Marsh.), pecan (Carya illinoensis Wangenh.), and northern red oak (Quercus rubra L.) were the most preferred species by C. formosanus in order of consumption rate. All of these species were significantly more preferred than southern yellow pine (Pinus taeda L.), widely used for monitoring. Sinker cypress [ = old growth bald cypress, Taxodium distichum (L.)], western red cedar (Thuja plicata Donn), Alaskan yellow cedar (Chamaecyparis nootkatensis D. Don), eastern red cedar (Juniperus virginiana L.), sassafras [Sassafras albidum (Nutt.)], Spanish cedar (Cedrella odorata L.), Honduras mahogany (Swietenia macrophyla King), Indian rosewood (Dalbergia latifolia Roxb.), Honduras rosewood (D. stevensonii Standl.), and morado (Machaerium sp.) induced significant feeding deterrence and mortality to C. formosanus. The last eight species produced 100% mortality after 3 mo.     

Nutritional ecology of the Formosan subterranean termite (Isoptera: Rhinotermitidae): growth and survival of incipient colonies feeding on preferred wood species

The wood of 11 plant species was evaluated as a food source significantly impacting the growth and survival of incipient colonies of the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). Colonies of C. formosanus feeding on pecan, Carya illinoensis (Wangenh.), and red gum, Liquidambar styraciflua L., produced significantly more progeny than colonies feeding on other wood species tested. Progeny of colonies feeding on pecan and American ash, Fraxinus americana L., had significantly greater survival than progeny of colonies feeding on other wood species. Colonies feeding on a nutritionally supplemented cellulose based matrix showed similar fitness characteristics as colonies feeding on the best wood treatments. These results indicate that differences observed in colony fitness can be partially explained by nutritional value of the food treatment, raising the possibility that wood from different tree species have different nutritional values to the Formosan subterranean termites. Colonies feeding on loblolly pine, Pinus taeda L., and ponderosa pine, Pinus ponderosa Laws., had significantly lower survival and produced significantly fewer workers and soldiers than colonies feeding on other wood species. Colony survival from 90 to 180 d of age and from 90 to 360 d of age was significantly correlated with the number of workers present at 90 d of colony age, indicating that colony survival depends on the presence of workers. Wood consumption in a multiple-choice study was significantly correlated with colony fitness value. This suggests that feeding preference of C. formosanus is at least partially influenced by the nutritional value of the food source.     

Areawide field study on effect of three chitin synthesis inhibitor baits on populations of Coptotermes formosanus and Reticulitermes flavipes (Isoptera: Rhinotermitidae)

Periodic sampling of 43 independent monitors, initially active with Formosan subterranean termite, Coptotermes formosanus Shiraki, or the eastern subterranean termite, Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae), was conducted to evaluate the effects of cellulose baits containing one of three chitin synthesis inhibitors (CSIs)-diflubenzuron, hexaflumuron, or chlorfluazuron-on termite populations. Diflubenzuron at 0.1% active ingredient (AI, wt:wt) had no noticeable effect on termite populations. Chlorfluazuron (0.25% [AI]) significantly reduced termite populations in approximately 3 yr. Chlorfluazuron used after > 2-yr diflubenzuron treatment significantly reduced termite populations within months. This suggests diflubenzuron exposure increased the termite's sensitivity to chlorfluazuron accelerating population collapse. Hexaflumuron (0.5% [AI]) also reduced termite populations in approximately 2 yr. The process of removing most detectable termite populations from the approximately 160,000-m2 campus of the Southern Regional Research Center, New Orleans, LA, with CSIs baits required approximately 3 yr. Adjustments in the specific bait formulations and application procedures might reduce time to suppression. Establishment of new independent termite populations provides a mechanism to minimize the effects of baits. Remedial control measures around and under structures should be considered when implementing an area wide management strategy.     

Field evaluation of a fipronil bait against subterranean termite Odontotermes formosanus (Isoptera: Termitidae)

The subterranean termite Odontotermes formosanus Shiraki is an important pest of agronomic crops, plantations, and forestry, and it endangers earthen dikes and dams in China. A fipronil bait consisting of straw pulp and white sugar was evaluated against field colonies of O. formosanus. Triple mark-capture with Nile blue dye was used to delineate foraging territories and to estimate foraging populations of four O. formosanus colonies locating in the campus of Huazhong Agricultural University, Wuhan, China. Termite activity was monitored by number of termite workers and straw board consumption in underground monitoring stations. Consumption of bait matrix and fipronil was estimated for each testing site. The results showed that approximately 3-5 mg of fipronil could suppress foraging populations of O. formosanus containing 0.4-0.7 million foragers per colony. Baits containing fipronil seem to be a feasible alternative for controlling O. formosanus.     

Effect of a lignin-degrading fungus on feeding preferences of Formosan subterranean termite (Isoptera: Rhinotermitidae) for different commercial lumber

The feeding preferences of the Formosan subterranean termite, Coptotermes formosanus Shiraki, for commercial lumber Alaska yellow cedar, Chamaecyparis nootkatensis (D. Don) Spach; yellow birch, Betula alleghaniensis Britton; northern red oak, Quercus rubra L.; redwood, Sequoia sempervirers (D. Don) Endl; and spruce (Picea spp.) were examined to determine whether the presence of the lignin-degrading basidiomycete Marasmiellus troyanus (Murrill) Singer could alter the relative preference of termites for these wood species. In paired choice tests with fungus-inoculated sawdust versus control sawdust, termites showed a strong preference for the fungus-inoculated sawdust for all wood species tested, except for Alaska yellow cedar. In a multiple-choice test using sawdust without fungus, termites showed a very strong preference for red oak sawdust over the other three species. In a paired choice test using fungus-inoculated sawdust, termites showed a preference for redwood over red oak sawdust. In a feeding test using autoclaved wood blocks without fungal decay, there was no difference in termite consumption of birch, red oak, or redwood. The relative preference of termites for redwood increased when blocks were decayed by M. troyanus for 3 and 8 wk. These results indicate that chemical modifications due to fungal decay affected the feeding preference of termites for different commercial lumber.     

Effect of Summon Preferred Food Source on feeding, tunneling, and bait station discovery by the formosan subterranean termite (Isoptera: Rhinotermitidae)

This study evaluated the effect of Summon Preferred Food Source on feeding, tunneling, and bait station discovery by the Formosan subterranean termite, Coptotermes formosanus Shiraki. Bioassays were conducted to determine whether Summon disks affected the aggregation and feeding behavior of termites and to determine whether the presence of Summon disks caused increased recruitment of termites to wood blocks. When termites encountered the disk, they immediately clustered on top of the disk. Termites were observed aggregating on top of the disk throughout the experiment. Consumption of Summon disks was significantly greater than consumption of cardboard disks in paired choice tests. The presence of a Summon disk on top of a wood block caused a significant increase in consumption of the wood block. Bioassays also were conducted to determine whether water extracts of Summon disks affected termite behavior. Consumption of filter paper disks treated with a water extract of Summon disks was significantly greater than consumption of control filter paper disks. Termites tunneled through sand treated with a water extract of Summon disks faster than they tunneled through untreated sand. In a field test, the rate of infestation of monitoring stations with a Summon disk was 3 times greater than the rate of infestations of stations without a disk.     

几种白蚁诱饵防霉剂的防霉效果比较

比较了8种供试防霉剂对黑翅土白蚁Odontotermes formosanus(Shiraki)喜食饵料小米粉的防霉效果,结果表明2‰山梨酸钾和0.75‰对小米粉的防霉效果较好,两者都能使野外试验坑中的小米粉样品8d后不发霉。室内试验结果表明,2‰山梨酸钾不影响黑翅土白蚁对小米粉的取食量;而0.75‰百菌清显著降低了黑翅土白蚁对小米粉的取食量,对黑翅土白蚁有明显的驱避作用。野外试验进一步表明,投饵8d后,小米粉诱饵、小米粉+2‰山梨酸钾诱饵、小米粉+0.75‰百菌清诱饵的发霉率分别为100,20和30%,而三者的被食率分别为27.67,53.70和19.15%。由此可见,2‰山梨酸钾最适合作为白蚁诱饵的防霉剂。     

Do the unique properties of nanometals affect leachability or efficacy against fungi and termites?

Nanotechnology has the potential to affect the field of wood preservation through the creation of new and unique metal biocides with improved properties. This study evaluated leachability and efficacy of southern yellow pine wood treated with copper, zinc, or boron nanoparticles against mould fungi, decay fungi, and Eastern subterranean termites. Results showed that nanocopper with and without surfactant, nanozinc, and nanozinc plus silver with surfactant resisted leaching compared with metal oxide controls. Nearly all nanoboron and boric acid was released from the treated wood specimens during leaching. Mould fungi were moderately inhibited by nanozinc oxide with surfactant, but the other nanometal preparations did not significantly inhibit mould fungi. Mass loss from Gloeophyllum trabeum was significantly inhibited by all copper preparations, while Antrodia sp. was not inhibited by nanometal treatments. Nanometals imparted high resistance in southern yellow pine to the white-rot fungus, Trametes versicolor. Unleached specimens treated with nanoboron or nanozinc plus surfactant caused 100% and 31% mortality, respectively. All specimens treated with nanozinc or nanozinc plus silver inhibited termite feeding, but the copper treatments were less effective against termites. Nanozinc possessed the most favorable properties: leach resistance, termite mortality, and inhibition of termite feeding and decay by the white-rot fungus.     

Effect of wood hardness and secondary compounds on feeding preference of Odontotermes formosanus (Isoptera: Termitidae)

Odontotermes formosanus (Shiraki) (Isoptera: Termitidae) is one of the most destructive plant pests in China, which control relies mainly on baits strategies. Baits made from the wood of eight different tree species were used to study the feeding preference of this termite, and conversely wood protection strategies of the tree species. Three bait types were used to identify wood protection strategies: solid wood (physical and chemical protection), crude flour (chemical protection) made from ground wood, and extracted flour (no protection) made by extracting crude flour with ethanol and toluene. Feeding preference was influenced by wood species and bait type. For solid wood, Magnolia denudata Desr (75%) and Elaeocarpus glabripetalus Merr (41%) were most preferred; for crude flour, E. glabripetalus (97%) and Quercus variabilis Blume (92%) were most preferred; and for extracted flour, there were no significant differences between wood species, demonstrating the influence of chemical defense. The greatest contrast between bait types was for Platanus orientalis L, the least preferred as solid wood and crude flour, suggesting that chemical defense compounds are particularly important in this species. Solid wood consumption was inversely correlated with wood density. Extracted flour consumption was positively correlated with glucose concentration. There was no direct effect of holocellulose and other components tested. O. formosanus preferred to fed on soft wood with low chemical protection (M. denudata); conversely trees protected their wood either physically [e.g., E. glabripetalus, Q. variabilis, Cinnamomum camphora (L.) Presl, and Ligustrum lucidum Aiton] or chemically (Populus bonati Levl) or a combination of both strategies (Liquidamba formosana Hance and P. orientalis).     

Landscape mulches and termite nutritional ecology: growth and survival of incipient colonies of Coptotermes formosanus (Isoptera: Rhinotermitidae)

Alate swarms are one of the major visible signs of the expansion of the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), in an area. Successful establishment of an incipient colony is thought to mainly rely on available food resources and moisture. The large-scale use of tree-based mulches in landscapes may inadvertently contribute to local establishment and growth of C. formosanus colonies. This research investigated the nutritional ecology of incipient colonies of C. formosanus feeding on seven tree-based, weathered, and nonweathered landscape mulches: pine straw, pine bark, cedar wood, water oak, eucalyptus, cypress, and melaleuca. Incipient colonies of C. formosanus feeding on pine straw, either weathered or nonweathered, produced significantly more progeny over the course of 1-yr feeding than colonies feeding on the other mulches tested. Regardless of weathered or not, the incipient colonies feeding on pine straw, eucalyptus, bald cypress, and water oak mulches had significantly greater survival rates after 360 d (53-77%) than colonies feeding on the other mulches tested (0-13%), but colonies feeding on nonweathered water oak had significantly lower survival (8%) than those kept on weathered water oak (58%). Colony fitness values were significantly different between the weathering treatment groups and among the different types of mulches. With regard to colony growth characteristics, three distinct growth patterns were identified: a high number of progeny (>100) with high colony survival rate (>50%), a medium number of progeny (12-50) with high colony survival rate (>50%), and a small number of progeny (0-10) with low colony survival rate (<5%). These findings suggest that different types of mulch substrates could significantly impact the nutritional ecology of the founding pairs and the successful establishment of incipient colonies during the swarming season.     

Feeding preference of Coptotermes formosanus (Isoptera: Rhinotermitidae) for gamma-irradiated wood impregnated with benzoylphenylurea compounds under laboratory conditions

The feeding preference of Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae) for 200-kGy gamma-irradiated Cryptomeria japonica D. Don (Japanese cedar) sapwood impregnated with benzoylphenylurea compounds such as hexaflumuron and noviflumuron was examined by three laboratory tests. Although termites were not deterred from feeding on gamma-irradiated wood samples that had been impregnated with hexaflumuron or noviflumuron, termite mortality was significantly higher compared with solvent controls in the no-choice test. All live termites were transferred to paper disks immediately after the no-choice test to investigate changes in mortality with time, and this test also confirmed the effects of hexaflumuron and noviflumuron on worker termites, which showed a significant feeding preference for gamma-irradiated wood. Only the 1480 ppm noviflumuron-impregnated gamma-irradiated wood specimens showed significant differences in mortality in the two-choice test. These results suggest that gamma-irradiated C. japonica wood, which is locally abundant in Japan, may have potential as a bait substrate for benzoylphenylurea compounds.     

Feeding site selection by workers of the Formosan subterranean termite Coptotermes formosanus (Isoptera: Rhinotermitidae) - a re-analysis of field data from a mark-recapture study

During the early stages of the development of termite baits, dyed paper was placed in specified feeding stations to ascertain whether a slow-acting toxicant could be placed in a few bait stations to be delivered to the entire colony members of the Formosan subterranean termite, Coptotermes formosanus Shiraki. Feeding frequency data, as measured by the dye concentration in individual termites, suggested the absence of feeding site fidelity. However, these results were often misinterpreted as random movement of termites that were marked and released for population estimate studies, or the random search of food in soil by subterranean termites. A computer simulation program was constructed to re-examine this feeding frequency data, and confirmed the earlier conclusion that the lack of feeding site fidelity was the most likely explanation for the data.     

Interactions of Metarhizium anisoplae and tree-based mulches in repellence and mycoses against Coptotermes formosanus (Isoptera: Rhinotermitidae)

The use of mulch in urban landscapes has increased in the United States for the past decade. Tree-based organic mulches can supply Coptotermes formosanus Shiraki with food, moisture, and shelter. The current research contributes to mulch management technology in termite control. A choice test arena was designed to determine the repellence and mortality caused by commercial mulches treated with different concentrations of the fungus Metarhizium anisopliae (Metschnikoff) against C. formosanus. Each of six tree-based mulches (pine bark, pine straw, bald cypress, eucalyptus, water oak, and melaleuca) was coated with six conidial concentrations ranging from 1 x 10(3) to 1 x 10(8) conidia/ml. The foragers of C. formosanus were repelled significantly by the fungal-treated mulch substrates; the proportion of termites on fungal-treated mulch was usually <20% during the 28-d test. By day 28, >99% of the termites were killed in test arenas containing a chamber with mulch treated with 10(7) or 10(8) conidia/ml. M. anisopliae significantly reduced mulch consumption by 34-71%. Mulch consumption by the termites was negatively correlated with fungal concentration, and the type of mulch also affected consumption. The differences in termite foraging activities, mortality, and food consumption among mulches were usually confounded by differences in fungal concentrations of M. anisopliae. The results indicate that repellence and virulence of M. anisopliae conidia should significantly reduce the suitability of these six mulches as a habitat for C. formosanus.     

Responses of Coptotermes formosanus and Reticulitermes flavipes (Isoptera: Rhinotermitidae) to three types of wood rot fungi cultured on different substrates

This study examined the responses of two termite species, the Formosan subterranean termite, Coptotermes formosanus Shiraki, and the eastern subterranean termite, Reticulitermes flavipes (Kollar), to three types of wood decay fungi: a brown rot fungus, Gloeophyllum trabeum (Persoon: Fries) Murrill; a white rot fungus, Phanerochaete chrysosporium Burdsall; and a litter rot fungus, Marasmiellus troyanus (Murrill) Singer. We also examined the responses of termites to these three types of fungi grown on different substrates. For all three fungal species, both termite species showed a strong preference for fungus-infected sawdust over uninfected sawdust. In choice tests, both termite species preferred sawdust infected with either M. troyanus or P. chrysosporium over G. trabeum. However, termites did not show any preference for fungus-infected potato dextrose agar over uninfected potato dextrose agar. Tunneling activity of C. formosanus was greater in sand treated with methanol extracts of fungus-infected sawdust than in sand treated with extracts of uninfected sawdust. Because chemicals in the fungal extracts caused termites to tunnel further into treated sand than untreated sand, these chemicals could potentially be used to direct termite foraging toward bait stations in the field.     

白蚁诱杀剂及其野外施药技术

2003~2004年在华中农业大学狮子山进行了白蚁诱杀剂野外施药技术研究。结果表明,地面蚁路法和枯枝内藏法对应小区的诱杀剂被食总量均较高,分别为26.78 g和22.84 g;而诱杀坑法、地表暴露法、树干粘贴法对应小区的诱杀剂被食总量均较低,分别为3.62,1.47,4.58 g。施药结束后1个月,地面蚁路法和枯枝内藏法对应小区的树木蚁害率分别比药前的减少了53.57%和43.24%,且地面无新鲜白蚁泥被;而诱杀坑法、地表暴露法、树干粘贴法对应小区的树木蚁害率分别比药前的增加了16.66%、17.65%和2.5%,且地面均布满了新鲜的白蚁泥被。施药结束后7个月,地面蚁路法和枯枝内藏法对应小区的2个黑翅土白蚁Odontotermes formosanus(Shiraki)巢体均死亡;而诱杀坑法、地表暴露法和树干粘贴法对应小区的3个黑翅土白蚁巢体均正常。     

Field Evaluations of Subterranean Termite Preference for Sap-Stain Inoculated Wood

Few studies have focused on interactions between subterranean termites and the ophiostomatoid fungal associates of pine bark beetles or root feeding weevils. Field stake tests were employed at four locations throughout Mississippi to determine the feeding preference of subterranean termites for blue-stained, unstained, and partially decayed southern pine sapwood stakes. This study also utilized wood decayed by Gloeophyllum trabeum, a fungus previously shown to elicit a positive subterranean termite feeding response, as a positive control. Stakes inoculated with G. trabeum received significantly more attacks than all other treatments after 16 weeks. Of the stakes attacked by subterranean termites, stakes inoculated with Ophiostoma minus were degraded faster than any other treatment. Subterranean termite preference for stakes treated with either of two Leptographium spp. and the untreated negative controls did not differ; however, each was fed upon less than all other treatments. The feeding rate on stakes inoculated with O. ips and G. trabeum being fed upon by subterranean termites was not significantly different. These results represent the first evidence of wood containing non-structurally degrading fungi (O. ips and O. minus) eliciting a feeding preference from subterranean termites greater than that of decayed wood. The implications of these results are particularly relevant to pine forest ecology, nutrient cycling, subterranean termite control, and the utilization of blue-stained southern pine building products in the southeastern U.S.     

Efficacy of vetiver oil and nootkatone as soil barriers against Formosan subterranean termite (Isoptera: Rhinotermitidae).

Vetiver oil and its components nootkatone and cedrene were assessed as sand treatments for their efficacy to disrupt food recruitment by Coptotermes formosanus Shiraki. Termites were required to tunnel through sand treated with vetiver oil, nootkatone, cedrene, or untreated sand to reach a food source. Results showed that sand treated with vetiver oil or nootkatone disrupted termite tunneling behavior. As a consequence, after 21 d, wood consumption and termite survival were significantly lower compared with cedrene-treated or untreated sand treatments. Sand treated with vetiver oil or nootkatone at 100 microg/g substrate were effective barriers to termites.     

白蚁巢系破坏堤坝稳定性的研究

黑翅土白蚁Odontotermes Formosanus是我国南方诸省严重危害堤坝的主要白蚁种。它的巢居结构严重破坏土质堤坝工程,常常形成险情或“千里金堤,溃于蚁穴”。 我们的试验说明了黑翅土白蚁的巢居结构破坏堤坝工程的原理,为防治白蚁提供理论依据。     

Use of a bait impact index to assess effects of bait application against populations of Formosan subterranean termite (Isoptera: Rhinotermitidae) in a large area

The effects of bait applications on the overall activity of the Formosan subterranean termite, Coptotermes formosanus Shiraki, in a town of 1.2 km2 were assessed between 2001 and 2003 by using a bait impact index. The index incorporated the amount of baits applied and the distance between bait application loci and the monitoring stations from which termite activity was measured. Even with the collaboration of only 35% of the residents and incomplete treatment records, the bait impact index demonstrated that more baits applied in proximity to monitoring loci significantly caused the decline of C. formosanus activity.     

Tunnel formation by Reticulitermes flavipes and Coptotermes formosanus (Isoptera: Rhinotermitidae) in response to wood in sand.

The tunneling responses of two subterranean termite species, Coptotermes formosanus Shiraki and Reticulitermes flavipes (Kollar), to the presence of sound wood in laboratory arenas were studied. Branching pattern and the speed of tunnel construction between R. flavipes and C. formosanus also were compared. Patlak's residence index (rho) was generated using the length, width, speed of construction, and area of the primary tunnels built by termites. In the same allotted time, C. formosanus built wider and shorter primary tunnels, whereas R. flavipes built thinner and longer primary tunnels. The presence of wood did not affect termite tunnel formation. This lack of variation in tunnel formation parameters was evidenced by the inability of the termites to locate wood sources over distance, even as short as 2.5 mm, and by the similar tunneling behaviors in areas of the arena with or without wood. Patlak's model predicted the densities of tunnels with an error between 9 and 28%. in experiments with R. flavipes exposed to a range of 0-8,000 g of wood, and between 61 and 87% in experiments with C. formosanus. These results indicated that the residence index can provide a qualitative measure of the effect of habitat heterogeneity on the individual termite tunnels. The tunneling constructions strategy of these subterranean termites is discussed.